Loud-speaker



Feb. 19, 1929.

A. H. BARTSCH ET AL LOUD SPEAKER 2 Sheets-$heet 1 Filed Feb. 5, 1926 Feb. 19, 1929. 1,702,926

A. H. BARTSCH ET AL LOUD SPEAKER Filed Feb. 5, 1926 2 Sheets-Sheet 2 Wood l 115775508 Wood L 22 mm ATTORNEYS Patented Feb. 19, 1929.

NITED STATES 1,702,926 PATENT OFFICE.

ALFRED H. BARTSCH, 0F SPRINGFIELD, MASSACHUSETTS, AND MARCUS C, HOPKINS,

OF WASHINGTON, DISTRICT OF COLUMBIA; SAID BARTSCH ASSIGNOR TO AMERI- GAN BOSCH MAGNET) CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK, AND SAID HOPKINS ASSIGNOR TO HOPKINS CORPORATION, OF JERSEY GITY, NEW JERSEY, A CORPORATION OF DELAWARE.

LOUD-SPEAKER.

Application filed February 5, 1926. Serial No. 86,123.

This invention relates to loud speakers and particularly to that type which embodies the use of a large conical diaphragm.

The diaphragm of cone type loud speakers is usually made of some fibrous material such as paper, impregnated cloth or the like. We have discovered that a conical diaphragm constructed at least partly of thin wood produces superior results. For instance, a conical diaphragm so constructed gives a very pleasing, soft and mellow tone to the reproduced sound. Moreover, the appearance of the loud speaker is greatly improved.

ln accordance with our invention we employ thin wood veneer in the construction of the diaphragm. We have found the Japanese wood veneer is well suited for the purpose. This veneer is obtainable in the form of thin sheets of wood ranging from about .00075 of an inch to about .001 of an inch in thickness, cemented to a tissue paper backing of about the same thickness, making the total thickness ofthe layer of wood and the backing range from about .0015 of an inch to .002 of an inch. Japanese wood veneer is so thin that a diaphragm constructed of it would not be self-supporting unless an impractical number of layers were used. W'e therefore, apply the veneer to a fibrous support or filler such as manila paper or craft paper by cementing one or more layers of the Japanese veneer to either one or both sides of the paper support in the manner hereinafter described more in detail. The composite sheet thus produced is formed into a cone preferably by cutting a sector from it and then folding the sheet to conical form and uniting the radial seam by gluing, stitching or the like.

One form of loud speaker constructed in accordance with the invention is illustrated in the accompanying drawings, in which:

Figs. 1 to 3 are respectively a front elevation, a side elevation and a rear elevation of the loud speaker;

Fig. 4 is a vertical transverse section of the speaker, and

The remaining figures are alternately fragmentary sections and perspective views illustrating various ways in which the Wood veneer may be applied to the paper support.

The type of speaker disclosed inthe drawlngs comprises a conical diaphragm 1 secured at its edge portion to the periphery of a dished sheet metal member 2. The sheet metal member 2 is in turn supported by a pedestal 3. The electromagnetic mechanism for actuating the cone is denoted in general at eland is preferably attached to and car-' ing applications of Marcus C.- I-Iopkins. J

The present invention pertains more particularly to the diaphragm per se, and to a loud speaker of general characteristics having a diaphragm of the particular construction herein disclosed.

The preferred way of constructing the diaphragm is to employ asheet of manila or craft paper and to cement or glue the I Japanese wood veneer to the sheet of pa er in any one of the various ways illustrate in Fi s; 5 to 8 inclusive.

ccording to Figs. 5 and 5* the Japanese wood veneer is applied to only one side of the paper support. In these figures the paper support is indicated at 8 and the Japanese wood veneer at 9 and 9', 9 being the wood veneer proper and 9' being the tissue paper backing to which the veneer roper is cemented. The combined sheet including the veneer 9 and the tissue paper backing 9 is glued directly to one face of the paper support 8. When onl one layer of the wood veneer is employed t e grain of the veneer may run in any direction. Fig. 5 shows in perspective a portion of the paper support 8 with the superposed layers of wood veneer 9 and tissue paper backing 9; and this figure also shows the graining on the veneer at 10.

In Figs. 6 and 6 two layers of the J apanese veneer are glued to one face of the wood veneer are preferably dispose back to back, that is, with the tissue paper backing 9 of one sheet abutting the tissue paper backing of the other sheet. The two sheets of Japanese veneer maybe cemented or glued to each other and then glued to the paper support 8, or one sheet ofthe J apanese wood veneer may be glued to the paper support and then the other sheet of Japanese veneer glued to the sheet first applied.

Where two sheets of veneer are employed as in F i 6, it is preferable, though not cssentia to apply the sheets of veneer to the paper support 1n such a way that the grain of one sheet is disposed at an angle, preferably at a right angle, to the 'rain of the other sheet. This is represented in Fig. 6 in which it will be noted that the grain of one sheet of the veneer is disposed at right angles to the grain 10 of the other sheet.

In Fig. 7 a sheet of Japanese veneer 9, 9' is applied to each face of the paper support 8. In this case it-is also preferable though not essential, to have the grain of one sheet of veneer at right angles to the grain of the other sheptof veneer as indicated in Fig. 7 h

In Fig. 8 two sheets of veneer 9, 9' are applied to each face of the paper support 8 and preferabl the two sheets of veneer on each-side of t e paper support 8 are placed back to back as described in connection-with Fig. 6. The same system of applying the veneer to the paper support 8 may be followed as descr1bed in connection with-Fig. 6. That. is, the veneer sheets at each side of the (paper support 8 may be cemented or glue in place successively or the two sheets at one side of the. paper support 8 may be first glued or cemented together and then a plied to the paper support. When two sl ieets of veneer are emplo ed at each side of the paper support as 1n ig58, the grain of the two sheets on one side of the paper.

support may run in the same direction and be isposed at right angles to the grain of the two sheets at the other side of the paper,

support. Preferably, however, the sheets of veneer are so applied that the grain of each sheet runs at ri t angles to the rain of the next adjoining sheet as illustrate in Fig. 8. However, if the grains of the two sheets at one side of the pa or support 8 are at right angles it is probab y immaterial whether the grains of the two inside sheets adjacent the paper support 8 are at right angles with respect-to each other or in the same direction.-

Any number of sheets of veneer may be applied either to one or both sides of the paper support following the various methods outlined above, provided the total thickness of the composite diaphragm does not exceed practical limits.

As above stated the wood veneer'which we employ is so thin that a diaphragm conto .008 of an inch making the total thickness of the composite diaphragm shown in inc to about .012 0 an inch.

By employing two sheets of wood veneer and so dis osing them that the grain of one runs at rig it an les to the grain of the other, the tendency o the diaphragm to warp is reduced to a minimum in spite of its thin character.

A diaphragm constructed as above described may be mounted in the sheet metal member 2 by providing the diaphra' m near its outer edge with' a circumferentia crease 11 to form a forwardly flaring brim portion 12. The sheet metal member 2 is provided with a corresponding offset forward- Figs 7 and 7 ran e from about .01 of any member 2 otherwise the conical portion of.

-the diaphragm would not be sufliciently free The best results are hadto vibrate axiall by securing the rim 12 of the diaphragm to the sheet metal member 2 throu bout a part only of its width as shown in ig'. 4 as this gives the cone substantial freedom for axialv movement. The outer layer of veneer may have a quick drying stain applied thereto to bring out and accentuate the graining in the woodthereby giving the loud speaker a very leasing appearance. The stain employed ,s ould not have a tendency to clo' the pores between the fibers' of the woo A very thin coating of wax may be' applied over the stain to protectthe veneer. d

We have found that the wood veneer greatly improves the sound producin propertles of t e diaphragm giving a p easing soft and mellow tone to the reproduced sound. The tone of the diaphragm apadherent 0i tissue paper e c1 the e 1 g 1 s s. ieyers 0i? eiieei' Ieemg pesitieneet mm. the c 1 l v q tissue paper eecmmgs ef each ei veeentaetisg reietien,

2y diazehreem fer Read spea v 009 veneer (Y1 st fitter ieyers 0:: a e

each le ee 0 M ier Emit} speak irisi W e fiiiez made 01 tWe e1 ieast @ne siele veneer? having; an tissue paper smi the 1 1 eer being pesiti ed eeniesi diaphragm made of fibrous material at least we mnerent facing of thin W006i veneer on at least one side seifi; dieiphiagm.

5. A lend speaker having a direct acting conical diaphragm ef fibrous inetei-isi and at least ene adherent facing of thin Wood veneer on least (me side of said e1iephzragm said Wood Veneer a thickness rang"- ing 20m about .00035 e2? inch to sbeut 01 0f em inch,

6. A 10nd speaker I" eenicai diaphragm 01? fibrous at ieastene adherent facing i Wood veneer on ieast ene side ciiep sgm said W002i veneer having an adhered; ieyer ei' tissue 7. A ieud. spe er aving a direct eenicai diaphragm 0. f? ateiisi ieest adhere: t veneer an at least phtagm, said Weed mess fiem LQ about .001 ef i eings ef W006i V6 ieyer ei" tissue pa} same thie wing 21 direct eating wetemei and having 2 4 "00075 e'i inch In testimeny we ALF JD Ho [V we PMLEC 

